Re: Question about commit message wrapping

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On Fri, 09 Dec 2011 02:59:06 +0100, Sidney San Martín <s@xxxxxxxxxxxx> wrote:

Hey, I want to ask about the practice of wrapping commit messages to 70-something charaters.

The webpage most cited about it, which I otherwise really like, is

	http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html

*Nothing else* in my everyday life works this way anymore. Line wrapping gets done on the display end in my email client, my web browser, my ebook reader entirely automatically, and it adapts to the size of the window.

Actually, opera-mail autowraps at 72 characters but sets the text format to flowed. It also wraps the quoted text when you reply. But there's a reasonable chance that you don't use opera in your daily life. On the other hand I would not be surprised if most decent e-mail clients worked that way.

Nobody's forcing you to use the same practice in your own projects anyway.



That article gives two reasons why commits should be wrapped to 72 columns. First:

git log doesn’t do any special special wrapping of the commit messages. With the default pager of less -S, this means your paragraphs flow far off the edge of the screen, making them difficult to read. On an 80 column terminal, if we subtract 4 columns for the indent on the left and 4 more for symmetry on the right, we’re left with 72 columns.

Here, I put a patch at the bottom of this email that wraps commit messages to, right now, 80 columns when they're displayed. (It’s a quick one, probably needs configurability. Also, beware, I don’t program in C too much.)

Hm. Saying "that's how the tool works" is not a good reason in my opinion. There might be tons of other reasons for wrapping at 80 characters. Readability is one that comes to mind for me.


Second:

git format-patch --stdout converts a series of commits to a series of emails, using the messages for the message body. Good email netiquette dictates we wrap our plain text emails such that there’s room for a few levels of nested reply indicators without overflow in an 80 column terminal. (The current rails.git workflow doesn’t include email, but who knows what the future will bring.)

There's been a standard for flowed plain text emails (which don't have to wrap at 80 columns) for well over ten years, RFC-2646 and is widely supported. Besides, code in diffs is often longer than 7x characters, and wrapping, like `git log`, could be done inside git. FWIW, there are a bunch of merge commits with lines longer than 80 characters in the git repo itself.

Yes, that standard allows e-mail clients to display the text more fluidly, even if the source text is word-wrapped. While git uses e-mail format, it isn't an e-mail client. I always interpreted this whole thing as git basically creating plain-text e-mails. You're actually writing the source of the e-mail in your commit message. If you care about actual use in e-mail (like we do here on the list) you might want to add the relevant header to the mails. That said, Apple Mail (the client you used to send your mail) doesn't even use the RFC you quote in the sent message. That mail is going to be a pain in the butt to read in mutt from work ;).



Finally, people read commits these days in many other places than `git log` (and make commits in many other places than a text editor configured to wrap). Most every GUI and already word wraps commit messages just fine. As a result, there are commits in popular repos much longer than the 72-column standard and no one notices. Instead, properly-formatted commit messages end up looking cramped when you see them in anywhere wider than 80 columns.

Cramped? I think it's compact and actually I prefer it over long lines.

Am I crazy?

Probably not. Don't take my word for it. I'm not a psychiatrist.


If this makes sense to anyone else, I'd be happy to help massage this into something git-worthy, with some help (never worked on Git before).

- - -

From a93b390d1506652d4ad41d1cbd987ba98a8deca0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sidney=20San=20Marti=CC=81n?= <s@xxxxxxxxxxxx>
Date: Thu, 8 Dec 2011 20:26:23 -0500
Subject: [PATCH] Wrap commit messages on display

- Wrap to 80 characters minus the indent
- Use a hanging indent for lines which begin with "- "
- Do not wrap lines which begin with whitespace
---
 pretty.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/pretty.c b/pretty.c
index 230fe1c..15804ce 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1243,8 +1243,14 @@ void pp_remainder(const struct pretty_print_context *pp,
 			memset(sb->buf + sb->len, ' ', indent);
 			strbuf_setlen(sb, sb->len + indent);
 		}
-		strbuf_add(sb, line, linelen);
-		strbuf_addch(sb, '\n');
+		if (line[0] == ' ' || line[0] == '\t') {
+			strbuf_add(sb, line, linelen);
+		} else {
+			struct strbuf wrapped = STRBUF_INIT;
+			strbuf_add(&wrapped, line, linelen);
+ strbuf_add_wrapped_text(sb, wrapped.buf, 0, indent + (line[0] == '-' && line[1] == ' ' ? 2 : 0), 80 - indent);

While on the subject, In my mail view, the new line started with the [1] from line[1], in the quote the line looks entirely different. Now this is code we're talking about, so it makes slightly more sense to have a proper wrapping hard-coded. Compare the above with the following:

+			int hanging_indent = ((line[0] == '-' && line[1] == ' ') ? 2 : 0);
[...]
+			strbuf_add_wrapped_text(sb, wrapped.buf, 0,
+									indent + hanging_indent,
+									80 - indent);

Much clearer, no? I personally usually have two or three terminals tucked next to each other, so I can look at two or three things at the same time. 80 characters limit is a nice feature then.


+			strbuf_addch(sb, '\n');
+		}
 	}
 }


Cheers,
Frans
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